A man works at the site of a rare earth metals mine at Nancheng county, Jiangxi province on October 20, 2010. (Stringer Shanghai/Reuters)

Two years after China limited its exports of “rare earth minerals,” unnerving developed countries that depended on them for industrial uses, production is expanding at sites outside China.

And as new sources of rare earth minerals have appeared, that has meant new jobs — including in the tiny town of China Grove, N.C., where Japan’s Hitachi Metals is planning to produce high-tech magnets from rare earth minerals.

The Hitachi plant and its 70 new manufacturing jobs are a small example of how market forces can sometimes undercut China’s trade clout.

In recent years, China has dominated the production of these magnets, in part because the country has had a virtual monopoly on the mining and refining of the rare earth elements used in their production.

There are 14 rare earth minerals commonly used in industrial applications. The elements are difficult to find in concentrations that can be commercially exploited. They provide, for example, the illumination in night-vision goggles. A fraction of a gram of elements such as dysprosium or Europium provide the colors that light up the screen of a smartphone. A hybrid car might contain 40 pounds or more of rare earth magnets — lighter and more powerful than traditional iron-based magnets — in the battery-based power chain or small motors that run power windows, seats and other accessories.

Hitachi Metals produces magnets that it hopes to sell to the makers of hybrid and electric cars.

“Just like any other supplier, we are trying not to be dependent on Chinese sources,” said Koshi Okamoto, executive director of New York-based Hitachi Metals America. “Reliable sources of supply are clearly one of the top priorities.”

North Carolina Secretary of Commerce J. Keith Crisco said that when the state was in talks with Hitachi about expanding, company officials said their other option was to make the magnets in China.

“We need to be good partners [with the Chinese]. Not pansies; good partners,” Crisco said. “They are a major economic force.”

Alarmed over Chinese restrictions on rare earth exports, the United States, the European Union and Japan filed a World Trade Organization complaint alleging that China was using its monopoly over the minerals as a political and economic weapon — for instance, to punish Japan over its claims to contested islands in the South China Sea and to entice companies to relocate factories inside China by offering a cheaper supply of rare earth materials.

Even as the United States was pursuing its WTO claim, Colorado-based Molycorp, along with firms in Australia and elsewhere, were reshaping the landscape. Molycorp reopened a rare earth mine in Mountain Pass, Calif., that had been shuttered a decade ago because the supply of the minerals coming from China was so cheap.

Molycorp President Mark A. Smith said the company, which has scaled up employment at the mine from 55 to 420 in recent years, aims to produce as much as 40,000 metric tons a year by 2013, accounting for about 30 percent of projected world supply.

As important, he said, the company recently acquired China-based Neo Materials and with it the technology needed to provide the more purely refined rare earth oxides used in computer, defense and telecommunications equipment.

At the peak of China’s influence on the market, he said, companies could get rare earth materials about 40 percent cheaper there than elsewhere. China used that advantage to recruit firms to the industrial regions near the source of the materials. Smith said the Chinese price and the world price have now nearly converged, and he predicted more announcements like Hitachi’s.

“As you see that diversity of supply, you’ll see R&D come back, and you’ll see manufacturing come back,” Smith said.